Seiichi Arima

Early detection of drought stress in tomato plants with chlorophyll fluorescence imaging–practical application of the speaking plant approach in a greenhouse–

Abstract The chlorophyll fluorescence imaging technique is useful for evaluating photosynthetic functions of plants without actually touching the plant. In our previous study, we developed a chlorophyll fluorescence imaging system for tomato plants cultivated in greenhouses. This imaging system measures the chlorophyll fluorescence induction phenomenon, a dynamic change in chlorophyll fluorescence intensity induced by illuminating a dark-adapted leaf with a stable intensity excitation light, and analyzes the shape of the induction curve, i.e., the temporal course of chlorophyll fluorescence intensity during this phenomenon. The shape of the induction curve is characterized by an initial maximum peak (P), subsequent transient dip (S), and secondary small peak (M). We defined an index, the photosynthetic function index (PFI; fluorescence intensity of P divided by the average fluorescence intensity from S to M), to evaluate the shape of the induction curve. In this study, we applied this system to detect drought stress in tomato plants cultivated in a semi-commercial greenhouse. PFI was clearly lower in stressed plants than in healthy plants. The decreased PFI in stressed plants is probably attributable to photosynthetic dysfunction in these plants.

Strawberry Harvesting Robot on Table-top Culture

In this paper, it is reported that a robot was developed for harvesting strawberry grown on table top culture. The robot mainly consisted of a 4 DOF manipulator, a harvesting end-effector using sucking force and a visual sensor. As its manipulator, a Cartesian coordinate type was adopted and it was suspended under the planting bed of strawberry. The robot was capable of moving along the planting bed without a traveling device because one prismatic joint of the manipulator played the role of a traveling device. The end-effector could suck a fruit using a vacuum device and it could compensate detecting errors caused by the visual sensor. The visual sensor gave the robot two dimensional information based on an acquired image and fruit depth was calculated as an average value of previously harvested fruit depths obtained from end-effector positions when the robot actually harvested. The end-effector moved toward a target fruit based on the three dimensional position of the target fruit until the fruit was detected by three pairs of photo-interrupters on sucking head. After cutting the peduncle by using the robots wrist joint, the fruits passed the tube and were transported to the tray. From the results of the harvesting experiments, it was observed that the robot could harvest all target fruits with no injury, and that depth measurement by a visual sensor was simplified because a distance between the robot and the fruits was kept an approximately constant by suspending the robot under the planting bed.

Traceability based on multi-operation robot; information from spraying, harvesting and grading operation robot

In this paper, a multi-operation robot to work in a strawberry field was designed and a traceability system based on information from the robot was explained. The multi-operation robot consisted of sections of a spraying robot, a harvesting robot and a grading robot. These robot sections recorded information on products as well as conducted precise operations. This information can be used for precision farming and traceability system opened to consumers.

Vision System for Cucumber-Harvesting Robot

Abstract A vision system was made and experimented for a cucumber-harvesting robot that harvests fruits on the cucumber plants trained along the inclined poles. The fruit was detected by specular-reflection sensors while the robot was traveling. The detected fruit was scanned by a 3-D vision sensor. Image recognition experiment was carried out using cucumber models that were made based on a real cucumber. The location and the size of the fruit could be recognized.

Strawberry Harvesting Robot on Hydroponic System

Abstract In this paper, robotic components were developed for harvesting strawberry grown on a hydroponic system. The robot mainly consisted of a manipulator, an end-effector and a visual sensor and could harvest fruits which hung down from hydroponic flumes. The manipulator was a polar coordinate type with five degrees of freedom, since there were few obstacles around the strawberry fruits. The end-effector could suck the fruit intoit by a blower so that detecting errors caused by a visual sensor could be compensated From a fundamental experimental result in laboratory, feasibility to harvest strawberry fruits by robot was found.

Development of a Multi-Operation System for Intelligent Greenhouses

Abstract To resolve the problem of declination of Japanese agriculture, plant factories with automation, quality control, robotization and speaking plant approach are necessary. The multi operation system described in this paper has running unit with automatic position sensing. Growth environment measurement unit has transpiration, photosynthesis, distance and temperature sensors to obtain plant growth information. The pest control unit uses the antiseptic effect of ozone water. The harvesting unit is used for cucumbers that grow fast; recognition of cucumbers ready to be harvested is achieved through distance information gathered by an attached photo interrupter and distance sensors. The development of multi-operation robot is continued by developing controlling program that can change the operating pattern by sharing the contents by each controlling and operating unit.

Root Temperature Control System Using Cold Water in Greenhouse

Air temperature in greenhouse is high for tomato plants in summer. It is important to maintain optimum temperature in greenhouse for yield. The cost of whole cooling in greenhouse is so expensive that local temperature control is suggested. Our previous research showed tomato plants with root cooling at 25 °C increased yields compared with those with no cooling. The chilled water can be used for root cooling system in greenhouse. The objective of this research was to evaluate the root cooling system using cold water for growing tomato plants in summer. Tomato plants were grown hydroponically in greenhouse. The cooling water flows into PVC pipe which is installed under cultivation bed. Water temperature was maintained at 12 °C. Inlet and outlet water in pipe and rockwool temperatures were measured. Our results showed that the rockwool temperature was maintained around 22°C with high air temperature (30°C) using root cooling system.